Sorry about that. I edited my post to remove my comment about the booster as a viable reverse loop switch. I've got a Digitrax DR5013 on order to test it out with the DR5033 booster. There are still some Digikeijs products for sale if you look for them.
I've got one reverse loop on the lower deck that is rather complex since it's not connected by 1 turnout.
Hopefully YaMoRC will have a solution when I need to wire up all the staging yard reverse loops on the top deck maybe next year. Meanwhile we have what we can get.
Incidently I've been using Digitrax BDL168s but got around the problem by using their RD2 (remote diode) in series with the block. All blocks within a power district come back to a single board. The RD2 allows thinner cable back to a BDL168 (I use alarm cable). To be honest the price of the NCE BD20 was a bit high.
As you can see I have a lot of wiring to rip out.
I also hope that all these questions are of general interest.
Oldngrey